Iode bienfaits et effets secondaires

Iodine: What are its side effects?

In a world where 2 billion people are affected by iodine deficiencydeficiency iodine-enriched food supplements seem to be an ideal solution. But are you aware of the possible side effects of excess iodine?

Yes, I am, iodinea vital mineral for thyroid function, and therefore for the body as a whole, is often taken lightly. Yet its use, especially in tablet form, can lead to a variety of adverse reactions, ranging from hyperthyroidism to allergic reactionsparticularly with iodinated contrast media in medical environments.

In this article, we'll be talking about side effects of excess iodine so that you can make informed choices for your well-being, in particular by opting for from quality iodine supplements and taking precautions precautions.

Iodine benefits and side effects table salt

We'll also discuss the essential benefits of iodine for our bodies, including its crucial role in thyroid function, cognitive development and metabolic regulation, underlining the importance of a balanced intake of this vital element for our overall health.

What are the side effects of excess iodine?

In the following section, we'll take you through them one by one the 10 main side effects to be feared from excessive iodine intakewhether due to a diet too rich in this trace element or to inappropriate supplementation/medication.

1. Hyperthyroidism (overactive thyroid)

Your thyroida small, butterfly-shaped gland located at the base of your neck (at the front of your neck). iodine to produce thyroid hormones. Thyroid hormones are crucial because they regulate many of your body's functionsfunctions, such as your metabolismyour energy and your body temperature.

Normally, your thyroid controls the amount of hormones it produces. However, your thyroid when you consume too much iodine - either through your diet or through dietary supplements - can sometimes upset this delicate balance. Your thyroid may start producing too many hormonesa condition known as hyperthyroidism [1].

Visit symptoms of hyperthyroidism include unexplained weight loss (where thyroid hormones stimulate metabolism and promote weight loss), a rapid heart ratefast heart rate nervousnessand fatiguefatigue heat intoleranceand sometimes neck swelling due to goiter [2].

It is important to understand that hyperthyroidism is not caused solely by an excess of iodine - other factors may also play a role [2]. However, if you take iodine supplements or consume iodine-rich foods, it's wise to do so with moderation and under medical supervisionespecially if you have thyroid problems.

2. Hypothyroidism (hypoactive thyroid)

Iodine benefits and side effects hypothyroidism

As mentioned above thyroid gland is like a that regulates many vital functions in your body, from your metabolism to your body temperature. In all this, you have to imagine iodine is like the fuel in this engine, because it's an element essential to the manufacture thyroid hormones.

However, any just as excess fuel can choke an engine, excessive iodine intake can sometimes slow down your thyroid, leading to hypothyroidism [3] !

This may seem surprising, given that iodine is often associated with improved thyroid function. But in some cases, voyour body reacts to excess iodine by decreasing thyroid hormone production to protect itself against what it perceives as an imbalance in thyroid function.. It's a bit like your thyroid pulling on the brake to avoid overheating! This is what we call a "hypothyroidism due to iodine overload".

If you develop hypothyroidism after taking too much iodineyou may experience symptoms due to an overall slowing down of your body caused by a lack of thyroid hormones [4] :

  • General fatigue or lethargy
  • weight gain.
  • Sensitivity to cold (chilliness)
  • Dry skin and brittle hair
  • Constipation
  • Depression
  • Slowing of cognitive functions
  • Irregular menstruation
  • Muscle and joint pain
  • Elevated levels of bad cholesterol (LDL), increasing the risk of cardiovascular problems)

Note that hypothyroidism can have several causes, including excess iodine is just one factor.

However, if you consume iodine-based dietary supplements or iodine-rich foodsit is essential to do so with sparingly and under medical supervisionespecially if you have a predisposition to thyroid imbalances.

3. Goiter

Iodine benefits and side effects goiter

Under normal circumstances, an adequate intake of iodine helps your thyroidthat little gland on the front of your neck, to function properly. However, an imbalance in this supply.., whether excessive or deficientcan lead to the development of goiteri.e. a visible increase in the size of the thyroid gland [5].

In the case of excess iodineyour thyroid can react by increasing in volume in an attempt to regulate iodine overabundance and maintain hormonal balance. This process can lead to visible swelling at the base of your neck (goiter).

The goiter associated with iodine excess is generally painlessbut it can sometimes cause discomfortby exerting pressure on other structures in the neck, which can lead to difficulty swallowing or breathing [6].

The goiter can also be the result of other factors, such as a iodine deficiencydeficiency autoimmune disorders or thyroid nodules. Therefore, if you notice a swelling in your neck, it is advisable to consult a health professional for an accurate diagnosis.

In order to prevent the risk of goiter linked to excess iodinean moderate and balanced consumption of this element is essential, whether via diet or through dietary supplements.

4. Thyroiditis

A excess iodine can also cause thyroiditisthyroiditis inflammation of the thyroid gland [7]. The latter generally manifests itself as a pain or sensitivity in the neck (where the thyroid is located), a fatiguefatigue low-grade fevera feeling of general malaise

In some situations, the thyroiditis iodine excess can lead to disruption of thyroid hormone productionproduction, leading to hyperthyroidism (increased production of thyroid hormones) or a hypothyroidism (reduced thyroid hormone production).

Therefore, if you are taking iodine-based dietary supplements and you notice the above-mentioned symptoms (neck sensitivity, fatigue...), stop supplementation and consult your therapist!

5. Allergic reaction

When you mention iodineit is essential to consider the possibility of allergic reactionsare rare in some people. If you use dietary supplements containing iodine or consume iodine-rich foodsit's important to be aware of this possibility.

In fact, for some people, exposure to iodine, especially in certain forms such as iodinated contrast media used in medical imagingcan trigger a allergic reaction [8].

Symptoms of an allergic reaction to iodine can vary in severity. They generally include skin rashrashes itchingand hivesand, in more serious cases angioedemawhich is a sudden and potentially dangerous swellingparticularly if it affects the respiratory tract.

It is important to distinguish between true allergic reactions and iodine intolerancewhich is more common and generally less severe. Symptoms of intolerance may include disturbances digestive disorders or mild skin rashes.

If you suspect allergic reaction to iodineit is imperative to consult a health professional immediately !

In addition, if you have ever had an allergic reaction to iodine, always inform your therapist before taking dietary supplements or undergoing medical examinations involving iodinated contrast media.

6. Digestive disorders

Iodine benefits and side effects digestion

Iodinealthough essential to your health, can sometimes be implicated in digestive disorders, especially if you consume high doseswhether through your diet or food supplements.

In fact, a excess iodine can have serious consequences.on your digestive system..

Here are some of the digestive disorders that may be associated with excessive iodine intake:

  • Nausea and vomiting,
  • Diarrhea or constipation,
  • Abdominal pain,
  • Heartburn and reflux.

7. Skin problems

Iodine can sometimes be associated with skin problems, especially when consumed in excess. Here's how it can manifest itself:

  • Acne and rashes Iodine stimulates sebaceous gland activity in the skin, which can lead to rashes or worsening of existing acne.
  • Dermatitis or urticaria Dermatitis or urticaria: some people may develop skin reactions such as dermatitis or urticaria in response to high iodine intake. These reactions usually manifest as redness, itching and rashes.
  • Allergic reactions Although rare, allergic reactions to iodine can also affect the skin, resulting in rashes, swelling and itching.

8. Heart problems

Iodine benefits and side effects heart

Iodine plays an essential role in thyroid function, and by extension, can influence heart health.

In fact, an imbalance, such as a excess iodinecan have worrying repercussions on your heart:

  • Heart palpitations and tachycardia Excess iodine can stimulate excessive thyroid hormone production, leading to hyperthyroidism. This can increase heart rate, causing palpitations or tachycardia (an abnormally rapid heartbeat).
  • Hypertension Hyperthyroidism (due to excess iodine) can also increase your blood pressure. An overactive thyroid speeds up bodily functions, including blood circulation, which can lead to hypertension.
  • Heart rhythm disorders In some cases, excess iodine and the resulting hormonal imbalances can lead to arrhythmias, where the heartbeat becomes irregular. This includes conditions such as atrial fibrillation (a rhythm disorder of the atria).
  • Angina and heart failure In more serious cases, and especially in people with a history of heart disease, the effects of hyperthyroidism on the heart can lead to angina pectoris (chest pain due to reduced blood supply to the heart) or an exacerbation of pre-existing heart failure.

9. Mineral imbalance

Excessive iodine intake can sometimes lead to an imbalance of other minerals in your body. Here's how this can manifest itself:

  • Interference with absorption of other minerals Excess iodine can interfere with the absorption of other essential minerals such as calcium, potassium and sodium. This can upset the mineral balance and affect various bodily functions.
  • Effects on calcium metabolism Excess iodine can influence calcium regulation in the body. The thyroid plays a role in calcium regulation, and a hormonal imbalance due to excess iodine can disrupt this process, leading to abnormal calcium levels.
  • Changes in sodium and potassium levels Thyroid hormones influence electrolyte balance. Overproduction of thyroid hormones due to excess iodine can lead to variations in sodium and potassium levels, which can affect muscular and cardiac function.
  • Risk of osteoporosis In cases where excess iodine leads to disturbances in calcium metabolism, this may increase the risk of osteoporosis, especially in post-menopausal women and the elderly.

10. Acute toxicity

The acute toxicity of iodinetoxicity, although rare, is a serious condition that occurs when a large quantities of iodine are ingested in a short space of time. This situation can lead to several serious symptoms and requires immediate medical attention! Here's what you need to know [9]:

  • Acute iodine toxicity often initially manifests itself as severe gastrointestinal symptomssuch as abdominal pain, nausea, vomiting and sometimes diarrhea.
  • High iodine ingestion can lead to metallic taste in the mouthaccompanied by burning sensations in the throat and stomach.
  • In severe cases, ingestion of large quantities of iodine can lead to angioedemaa rapid and potentially dangerous swelling of tissues, particularly around the throat and respiratory tract.
  • Massive iodine intake can significantly disrupt thyroid function, leading to acute hormonal imbalances such as hyperthyroidism or hypothyroidism.
  • In the most extreme cases, acute iodine toxicity can lead to kidney, heart and other organ damagedue to the corrosive effect of iodine at high concentrations.

It is crucial to understand that acute iodine toxicity is generally associated with the ingestion of doses, far in excess of those found in standard food supplements or a balanced diet. It is most often associated with accidentsaccidents overdose of iodine-based medicinesor exposure to iodinated industrial chemicals.

Properly taken, iodine is a precious ally for your health!

Iodine benefits and side effects healthy family iodine

Iodine, a essential to your well-beingoffers numerous health benefitswhich makes iodine-based dietary supplements a a wise choice for many people. Here are the main benefits of iodine [10] - [13] :

  • Support of thyroid function Iodine: Iodine is crucial for the production of thyroid hormones, which regulate metabolism, energy and growth. Adequate iodine intake ensures your thyroid functions properly.
  • Cognitive development For pregnant women and young children, iodine plays a vital role in brain development. Adequate iodine intake during pregnancy and childhood is essential for optimal cognitive development.
  • Prevention of thyroid disorders Regular iodine consumption can help prevent thyroid-related disorders such as goiter (enlarged thyroid gland) and hypothyroidism.
  • Skin health Skin health: Iodine contributes to skin health, helping to keep it hydrated and regenerate skin cells.
  • Immune function Iodine plays a role in supporting the immune system, helping your body to fight infections.
  • Regulation of the menstrual cycle In women, adequate iodine intake can help regulate the menstrual cycle and reduce certain symptoms of premenstrual syndrome.
  • Reproductive health Iodine plays a role in reproductive health for both men and women.

Taking iodine tablets or iodine-based food supplements can be particularly beneficial if you live in a region where iodine is scarce in the soil and diet. This can help make up for dietary deficiencies and ensure sufficient intake for your body's proper functioning.


Iodine proves to be a exceptional health allyplaying a key role in maintaining many of your body's essential functions. From thyroid regulation of your metabolism to cognitive development, skin health and immune function, the benefits of iodine are multiple and and varied.

However, as with any nutrient, balance is crucial. A intake iodine intakeeither through your diet or through dietary supplementscan make a major contribution to your general well-being, while preventing disorders linked to deficiency or excess.


  1. J. b. Stanbury et al.Iodine-Induced Hyperthyroidism: Occurrence and Epidemiology, Thyroid®vol. 8, no.o 1, pp. 83-100, Jan. 1998, doi: 10.1089/thy.1998.8.83.
  2. ["Hyperthyroidism - Hormonal and metabolic disorders", MSD Manuals for the general public. Accessed: November 17, 2023.
  3. [K. Markou, N. Georgopoulos, V. Kyriazopoulou, and A. g. Vagenakis, "Iodine-Induced Hypothyroidism." Thyroid®vol. 11, no 5, p. 501-510, May 2001, doi: 10.1089/105072501300176462.
  4. "Hypothyroidism - symptoms, causes, treatment and prevention - VIDAL. Accessed: November 18, 2023.
  5. "Excess iodine - Nutritional disorders", MSD manuals for the general public. Accessed: November 17, 2023.
  6. "Thyroid goiter", Rothschild Foundation Hospital. Accessed on: November 18, 2023.
  7. N. R. Rose, R. Bonita, and C. L. Burek, "Iodine: an environmental trigger of thyroiditis", Autoimmun. Rev.vol. 1, no 1, p. 97-103, Feb. 2002, doi: 10.1016/S1568-9972(01)00016-7.
  8. N. R. Wulf, J. Schmitz, A. Choi, and J. Kapusnik-Uner, "Iodine allergy: Common misperceptions", Am. J. Health. Syst. Pharm.vol. 78, no.o 9, pp. 781-793, May 2021, doi: 10.1093/ajhp/zxab033.
  9. J. A. T. Pennington, "A review of iodine toxicity reports, J. Am. Diet. Assoc.vol. 90, no 11, pp. 1571-1582, Nov. 1990.
  10. N. Bleichrodt, R. M. Shrestha, C. E. West, J. G. Hautvast, F. J. Van De Vijver, and M. P. Born, "The benefits of adequate iodine intake." Nutr. Rev.vol. 54, no.o 4, p. S72-S78, 1996.
  11. F. Delange and P. Lecomte, "Iodine Supplementation: Benefits Outweigh Risks", Drug Saf.vol. 22, no 2, p. 89-95, 2000, doi: 10.2165/00002018-200022020-00001.
  12. F. Delange, "Risks and benefits of iodine supplementation", The Lancetvol. 351, no 9107, p. 923-924, 1998.
  13. D. W. Miller, "Extrathyroidal benefits of iodine, J. Am. Physicians Surg.vol. 11, no 4, p. 106, 2006.
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